JP3069281B2 - Optical scanning optical system - Google Patents
Optical scanning optical systemInfo
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- JP3069281B2 JP3069281B2 JP34645795A JP34645795A JP3069281B2 JP 3069281 B2 JP3069281 B2 JP 3069281B2 JP 34645795 A JP34645795 A JP 34645795A JP 34645795 A JP34645795 A JP 34645795A JP 3069281 B2 JP3069281 B2 JP 3069281B2
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- Prior art keywords
- scanning direction
- optical
- sub
- optical system
- convex lens
- Prior art date
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Description
【０００１】[0001]
【発明の属する技術分野】本発明は、レーザ光源からの
光束を偏向反射面を有する光偏向器により偏向させ、該
偏向光束を光走査光学系により被走査面上に光スポット
として集光させて光走査を行なう光走査光学系に関す
る。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of deflecting a light beam from a laser light source by an optical deflector having a deflecting and reflecting surface, and condensing the deflected light beam as a light spot on a surface to be scanned by an optical scanning optical system. The present invention relates to an optical scanning optical system that performs optical scanning.
【０００２】[0002]
【従来の技術】レーザ光源からの光束を回転多面鏡や回
転単面鏡、回転２面鏡等の「偏向反射面を有する光偏向
器」により等角速度的に偏向させ、偏向光束を光走査光
学系により被走査面上に光スポットとして集光させて光
走査を行なう光走査装置が、光プリンターやデジタル複
写機等において広く知られている。2. Description of the Related Art A light beam from a laser light source is deflected at an equal angular velocity by an "optical deflector having a deflecting and reflecting surface" such as a rotary polygon mirror, a rotary single-surface mirror, or a rotary two-surface mirror, and the deflected light beam is scanned by optical scanning. 2. Description of the Related Art An optical scanning device that performs optical scanning by condensing light as a light spot on a surface to be scanned by a system is widely known in optical printers, digital copying machines, and the like.
【０００３】この光走査装置において、回転多面鏡では
複数の偏向反射面の回転軸に対する平行度の「ばらつ
き」によって、また回転単面鏡や回転２面鏡においても
回転軸の「ぶれ」によって、光スポットの走査線位置が
副走査方向へ変動する所謂「面倒れ」の問題がある。[0003] In this optical scanning device, the rotating polygon mirror causes "variation" in the parallelism of the plurality of deflecting / reflecting surfaces with respect to the rotation axis, and the rotating single face mirror or rotating two-face mirror also suffers from "blur" in the rotation axis. There is a problem of so-called "surface tilt" in which the scanning line position of the light spot varies in the sub-scanning direction.
【０００４】この面倒れを補正する有効な方法とし、従
来より光源からの光束を副走査方向に関して、偏向反射
面近傍の位置に主走査方向に線像として結像させ、光走
査光学系には副走査方向に関して偏向反射面位置と被走
査位置とを幾何光学的な共役関係とする機能を付与する
ことが行なわれている。このような光走査装置の光走査
光学系は、主走査方向のパワーと副走査方向のパワーと
が異なる「アナモフィック」な結像光学系となる。As an effective method for correcting this surface tilt, a light beam from a light source has conventionally been formed as a line image in the main scanning direction at a position near the deflecting reflection surface in the sub-scanning direction. There has been provided a function of making the position of the deflecting reflection surface and the position to be scanned a geometric conjugate relationship in the sub-scanning direction. The optical scanning optical system of such an optical scanning device is an “anamorphic” imaging optical system in which the power in the main scanning direction and the power in the sub-scanning direction are different.
【０００５】[0005]
【発明が解決しようとする課題】ところで光走査装置に
より良好な光走査を実現するには、「光スポット径が像
高により大きく変動しない」こと、及び「光スポットの
移動速度が等速度である」ことが必要である。このうち
「光スポット径の像高による変動」は、光走査光学系の
像面湾曲により発生するが、光スポット径に像高による
変動があると、光走査により書き込まれる画像の解像力
が均一にならない。主走査方向に関しては、光スポット
径に多少の変動があっても偏向光束に乗せる信号を電気
的に制御することにより補正が可能であるが、副走査方
向の光スポット径変動はこのような補正ができない。ま
た「光スポットの移動速さの等速性」は、光走査光学系
のｆθ特性と副走査方向の像面湾曲とが良好に補正され
ていなければならない。しかしアナモフィックなレンズ
においては、ｆθ特性と副走査方向の像面湾曲とを同時
に良好に補正することは容易ではなく、複数枚のレンズ
を組み合わせて光走査光学系を構成している。However, in order to realize good optical scanning by the optical scanning device, it is necessary that "the light spot diameter does not fluctuate greatly with the image height" and that "the moving speed of the light spot is constant. "It is necessary. The “fluctuation of the light spot diameter due to the image height” is caused by the field curvature of the optical scanning optical system. If the light spot diameter fluctuates due to the image height, the resolution of the image written by the optical scanning becomes uniform. No. Regarding the main scanning direction, even if there is a slight variation in the light spot diameter, correction can be made by electrically controlling the signal to be carried on the deflected light beam. Can not. Further, the “constant speed of the moving speed of the light spot” requires that the fθ characteristic of the optical scanning optical system and the curvature of field in the sub-scanning direction be properly corrected. However, in an anamorphic lens, it is not easy to simultaneously satisfactorily correct the fθ characteristic and the field curvature in the sub-scanning direction, and an optical scanning optical system is configured by combining a plurality of lenses.
【０００６】例えば、凸レンズによってｆθ特性を補正
しようとした場合に、主走査方向の収差（主走査方向像
面とｆθ特性）を満足させると、凸レンズの被走査面側
の面（後面）が偏向反射面側の面（前面）より曲率が大
きくなるが、このとき走査光学系を単レンズで満足させ
ようとすると、被走査面側の面（後面）をトーリック面
として偏向反射面と被走査面を共役にする必要があり、
副走査像面が補正不足になる傾向がある。このトーリッ
ク面による像面湾曲特性及びｆθ特性の一例を、図５
（ａ）及び（ｂ）に示す。図５（ａ）中の破線は主走査
方向の像面を表し、図中実線は副走査方向の像面を表し
ている。For example, when the fθ characteristic is to be corrected by a convex lens, if the aberration in the main scanning direction (the image plane in the main scanning direction and the fθ characteristic) is satisfied, the surface (rear surface) of the convex lens on the scanned surface side is deflected. Although the curvature becomes larger than the surface on the reflection surface side (front surface), if the scanning optical system is to be satisfied with a single lens, the surface on the scan surface side (rear surface) is a toric surface and the deflection reflection surface and the scan surface are used. Must be conjugated,
The sub-scanning image plane tends to be under-corrected. FIG. 5 shows an example of the field curvature characteristic and the fθ characteristic by the toric surface.
(A) and (b). The broken line in FIG. 5A represents the image plane in the main scanning direction, and the solid line in the figure represents the image plane in the sub-scanning direction.
【０００７】このように従来では、１枚の凸レンズで
は、主走査方向の像面及びｆθ特性と副走査方向の像面
湾曲補正とを同時に良好に得ることは困難であり、例え
ば特開昭６３ー２１０８１５号のように、凸レンズから
なるｆθレンズに、像面を補正する補正レンズを別個に
組み合せて構成しており、そのため全体の構成が複雑化
し生産性の低下を招来している。As described above, conventionally, it is difficult for a single convex lens to simultaneously obtain good image plane and fθ characteristics in the main scanning direction and good correction of the field curvature in the sub-scanning direction. As described in JP-A-210815, a correction lens for correcting an image plane is separately combined with an fθ lens composed of a convex lens, which complicates the entire configuration and causes a decrease in productivity.
【０００８】そこで本発明は、主走査方向の像面及びｆ
θ特性と副走査方向の像面湾曲の補正とを、１枚の凸レ
ンズにより良好に得ることができるようにした光走査光
学系を提供することを目的とする。Accordingly, the present invention provides an image plane in the main scanning direction and f
It is an object of the present invention to provide an optical scanning optical system in which the θ characteristic and the correction of the curvature of field in the sub-scanning direction can be favorably obtained by one convex lens.
【０００９】[0009]
【課題を解決するための手段】上記目的を達成するため
本発明は、主走査方向においてｆθ機能を有するととも
に、副走査方向において偏向反射面位置と被走査面位置
とを幾何光学的に略共役な関係とすることによって、副
走査方向の面倒れを補正する補正機能を有する光走査光
学系において、上記被走査面側の面が主走査方向及び副
走査方向の両方向に凸をなす１枚の凸レンズにより構成
され、上記凸レンズの被走査面側面が、中心光軸に平行
で主走査方向に直交する平面による断面形状に関して主
走査方向に一定である面構成になされている。In order to achieve the above object, the present invention has an fθ function in the main scanning direction and substantially geometrically optically conjugates the position of the deflecting reflection surface and the position of the surface to be scanned in the sub-scanning direction. In the optical scanning optical system having a correction function of correcting surface tilt in the sub-scanning direction, the surface on the side to be scanned has one surface protruding in both the main scanning direction and the sub-scanning direction. The scanning lens has a convex surface, and the side surface of the surface to be scanned of the convex lens is mainly a cross-sectional shape of a plane parallel to the central optical axis and orthogonal to the main scanning direction.
The surface configuration is constant in the scanning direction.
【００１０】本発明においては、例えば図１（ａ）に示
されているように、光偏向器を構成する回転多面鏡１の
偏向反射面１ａで反射された光束が、本発明にかかる光
走査光学系を形成する凸レンズ２を通して、感光体ドラ
ム３の被走査面３ａ上に結像・走査されるように構成さ
れており、上記光走査光学系を形成する凸レンズ２の被
走査面側の面すなわち光出射面は、上述したようなアナ
モフィック面に形成されている。このアナモフィック面
は、図１（ｂ）に示されているように、中心光軸２ａに
平行で主走査方向に直交する平面Ｄ1 による断面形状Ｄ
2 が長手方向に略一定又は同一の曲率半径である面構成
になされており、この面構成によって主査方向における
像面及びｆθ特性と、副走査方向における像面湾曲の補
正とを同時に得るようになっている。なお上記凸レンズ
２の偏向面側すなわち回転多面鏡１側には、副走査方向
倍率調整用のレンズ４が配置されている。この副走査方
向倍率調整用のレンズ４は、上記凸レンズ２の主走査方
向の倍率を変えたときに副走査方向の倍率を調整するた
めのレンズであるので必ずしも設ける必要はない。In the present invention, for example, as shown in FIG. 1A, the light beam reflected by the deflecting / reflecting surface 1a of the rotary polygon mirror 1 constituting the optical deflector is used for optical scanning according to the present invention. An image is formed and scanned on the scanned surface 3a of the photosensitive drum 3 through the convex lens 2 forming the optical system, and the surface on the scanned surface side of the convex lens 2 forming the optical scanning optical system is configured. That is, the light emitting surface is formed on the anamorphic surface as described above. As shown in FIG. 1B, the anamorphic surface has a sectional shape D defined by a plane D1 parallel to the central optical axis 2a and orthogonal to the main scanning direction.
2 has a surface configuration that is substantially constant or has the same radius of curvature in the longitudinal direction, so that the surface configuration and the fθ characteristic in the main scanning direction and the correction of the field curvature in the sub-scanning direction are simultaneously obtained by this surface configuration. Has become. A lens 4 for adjusting the magnification in the sub-scanning direction is arranged on the deflection surface side of the convex lens 2, that is, on the rotary polygon mirror 1 side. The lens 4 for adjusting the magnification in the sub-scanning direction is not necessarily provided because it is a lens for adjusting the magnification in the sub-scanning direction when the magnification of the convex lens 2 in the main scanning direction is changed.
【００１１】このように本発明によれば、主走査方向及
び副走査方向の両方向に正のパワーを有しかつ中心光軸
に平行で主走査方向に直交する平面による断面形状が長
手方向に略一定であるアナモフィック面を被走査面側に
有する１枚の凸レンズ２によって、主走査方向の像面及
びｆθ特性が良好に得られると同時に、副走査方向にお
ける像面湾曲の補正が良好に行なわれる。As described above, according to the present invention, the cross-sectional shape of a plane having a positive power in both the main scanning direction and the sub-scanning direction and being parallel to the central optical axis and orthogonal to the main scanning direction is substantially longitudinal. With a single convex lens 2 having a constant anamorphic surface on the surface to be scanned, an image surface in the main scanning direction and fθ characteristics can be obtained well, and at the same time, field curvature in the sub-scanning direction can be corrected well. .
【００１２】[0012]
【発明の実施の形態】以下、本発明の実施形態を詳細に
説明する。以下述べる各実施形態は、その前提として、
レーザ光源からの光束が平行光束化された後、副走査方
向へのみ収束させられ、光偏向器の偏向反射面の近傍に
「主走査方向に長い線像」として結像される。そして光
偏向器によって等角速度的に偏向され、光走査光学系を
通して被走査面上に光スポットとして集光させられるよ
うに構成されている。DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail. Each embodiment described below is based on the premise that
After the light beam from the laser light source is converted into a parallel light beam, it is converged only in the sub-scanning direction, and is formed as a "long line image in the main scanning direction" near the deflecting reflection surface of the optical deflector. The light is deflected at a constant angular velocity by an optical deflector, and condensed as a light spot on a surface to be scanned through an optical scanning optical system.
【００１３】従って本発明にかかる光走査光学系におい
ては、主走査方向に関して「光源側の無限遠と被走査面
の位置」とがピントの合う位置関係、すなわち共役関係
になされ、副走査方向に関して「偏向反射面の位置と被
走査面の位置」とが共役関係になされている。Therefore, in the optical scanning optical system according to the present invention, the "infinity on the light source side and the position of the surface to be scanned" are in a focused positional relationship, that is, a conjugated relationship with respect to the main scanning direction. The “position of the deflecting reflection surface and the position of the surface to be scanned” are in a conjugate relationship.
【００１４】図３に示されている本発明の第１実施形態
における光走査光学系は、上述したアナモフィック面を
有する１枚の凸レンズ２１から構成されている。そして
図示を省略した光偏向器の偏向反射面を符号「１」で表
し、本発明にかかる凸レンズ２１の偏向反射面側の面
（前面）を符号「２」で表し、当該凸レンズ２１の被走
査面側の面（後面）を符号「３」で表している。このと
きレンズ面の主走査方向における曲率半径ｒi （以下、
沿字ｉは上記各面の符号に対応する）、副走査方向にお
ける曲率半径ｒ’i、ｉ番目の面から（ｉ＋１）番目の
光軸上の間隔ｄi、レーザ光源の波長７８０ｎｍに対す
る屈折率ｎi は、それぞれ以下のような値にて構成され
ている。The optical scanning optical system according to the first embodiment of the present invention shown in FIG. 3 includes one convex lens 21 having the above-described anamorphic surface. The deflecting / reflecting surface of the optical deflector (not shown) is represented by reference numeral “1”, the surface on the deflecting / reflecting surface side (front surface) of the convex lens 21 according to the present invention is represented by reference numeral “2”, and the convex lens 21 scans the convex lens 21. The surface on the surface side (rear surface) is represented by reference numeral “3”. At this time, the radius of curvature ri of the lens surface in the main scanning direction (hereinafter, referred to as ri)
The suffix i corresponds to the sign of each surface described above), the radius of curvature r'i in the sub-scanning direction, the distance di from the i-th surface on the (i + 1) -th optical axis, and the refractive index ni for the laser light source at a wavelength of 780 nm. Are composed of the following values, respectively.
【００１５】 ｉ ｒi ｒ’i ｄi ｎi １ 0.0000 0.0000 32.6000 1.00000 ２ 183.4000 183.4000 16.9500 1.48601 ３ -64.1300 -15.4000 97.0000 1.00000 Irir'idinni 1 0.0000 0.0000 32.6000 1.00000 2 183.4000 183.4000 16.9500 1.48601 3 -64.1300 -15.4000 97.0000 1.00000
【００１６】ここで第１面は光偏向器の偏向反射面であ
り平面であるが、便宜上ｒ1＝0.0000と表してある。次
に、第２面は、 ｘ＝（１／ｒ）ｙ2 ／｛１＋√［１−（１＋ｋ）ｙ2 ／
ｒ2 ］ ｝＋ａｙ4 ＋ｂｙ6 ＋ｃｙ8 ＋ｄｙ10 で表される回転非球面ｘとして構成されており、上式に
おける非球面係数は、 ｋ＝ 0.00000E+00 ａ＝-0.89700E-06 ｂ＝ 0.27800E-09 ｃ＝ 0.00000E+00 ｄ＝-0.24600E-16 但し、ｒ＝ｒ2＝ｒ’2 ａ＝-0.89700E-06 は -0.89700×10-6 を表す（以下
同じ）。である（尚、光軸点での曲率半径はｒ2＝ｒ’2
＝183.4000で等しくなる）。Here, the first surface is a deflecting / reflecting surface of the optical deflector and is a flat surface, but is expressed as r1 = 0.0000 for convenience. Next, the second surface, x = (1 / r) y 2 / {1 + √ [1- (1 + k) y 2 /
r 2]} + ay 4 + by 6 + cy is configured as a rotating aspheric x represented by 8 + dy 10, aspherical surface coefficients in the above equation, k = 0.00000E + 00 a = -0.89700E-06 b = 0.27800 E-09 c = 0.00000E + 00 d = -0.24600E-16 where r = r2 = r'2 a = -0.89700E-06 represents -0.89700 × 10 -6 (the same applies hereinafter). (The radius of curvature at the optical axis point is r2 = r'2
= 183.4000).
【００１７】また焦点距離ＦＬは、ＦＬ＝100.003 であ
る。次に、第３面は凸レンズ２１の被走査面側の面（後
面）であり、ｒ3＝-64.1300，ｒ’3＝-15.4000で表され
るように、主走査方向及び副走査方向の両方向に正のパ
ワー（集束性）を有しており、かつ中心光軸に平行で主
走査方向に直交する平面による断面を見たとき、その断
面形状が長手方向、即ち、主走査方向のどの点で見ても
同一の曲率半径である一定の面形状になっている。The focal length FL is FL = 100.003. Next, the third surface is the surface (rear surface) on the surface to be scanned of the convex lens 21, and is expressed in both the main scanning direction and the sub-scanning direction as represented by r3 = -64.1300 and r'3 = -15.4000. When a cross section of a plane having a positive power (converging property) and being parallel to the central optical axis and orthogonal to the main scanning direction is viewed, the cross-sectional shape is in the longitudinal direction, that is, at any point in the main scanning direction. Even if it sees, it has a constant surface shape with the same radius of curvature.
【００１８】また図２に示されているように、光偏向器
１の回転中心をＯ、光偏向器１の内接円半径をＰr 、光
偏向器１の偏向反射面１ａと光走査光学系の凸レンズ２
の光軸２ａとの交差点すなわち光偏向器１の偏向反射面
１ａに対する入射光軸２ｂの入射点をＡ、その入射点Ａ
において入射光軸２ｂが光軸２ａとなす角度をθ、上記
入射点Ａから光偏向器１の回転中心Ｏに至る光軸方向及
び光軸直交方向の各距離をＰx 及びＰy としたとき、上
記第１実施形態においては、 Ｐr ＝１３．２ θ ＝８０° Ｐx ＝１０．１７ Ｐy ＝ ８．８２ である。As shown in FIG. 2, the center of rotation of the optical deflector 1 is O, the radius of the inscribed circle of the optical deflector 1 is Pr, the deflecting / reflecting surface 1a of the optical deflector 1 and the optical scanning optical system. Convex lens 2
A is the point of intersection of the optical axis 2a with the optical axis 2a, that is, the incident point of the incident optical axis 2b with respect to the deflecting / reflecting surface 1a of the optical deflector 1,
In the above, when the angle between the incident optical axis 2b and the optical axis 2a is θ, and the distances in the optical axis direction and the optical axis orthogonal direction from the incident point A to the rotation center O of the optical deflector 1 are Px and Py, In the first embodiment, Pr = 13.2 θ = 80 ° Px = 10.17 Py = 8.82
【００１９】このような第１実施形態にかかる像面湾曲
特性及びｆθ特性を、図４（ａ）及び（ｂ）に示す。こ
のうち図４（ａ）中の破線は主走査方向の像面を表し、
図中実線は副走査方向の像面を表している。FIGS. 4A and 4B show the field curvature characteristic and the fθ characteristic according to the first embodiment. Among these, the broken line in FIG. 4A represents the image plane in the main scanning direction,
The solid line in the figure represents the image plane in the sub-scanning direction.
【００２０】次に図６に示されている本発明の第２実施
形態における光走査光学系も、上述したアナモフィック
面を有する１枚の凸レンズ２２から構成されているが、
上記凸レンズ２２の偏向面側すなわち回転多面鏡側に
は、副走査方向倍率を下げたときに副走査方向の像面を
主走査方向の像面に一致させるための倍率調整レンズ２
３が配置されている。Next, the optical scanning optical system according to the second embodiment of the present invention shown in FIG. 6 also includes one convex lens 22 having the above-described anamorphic surface.
On the deflection surface side of the convex lens 22, that is, on the rotating polygon mirror side, a magnification adjusting lens 2 for making the image plane in the sub-scanning direction coincide with the image plane in the main scanning direction when the magnification in the sub-scanning direction is lowered.
3 are arranged.
【００２１】そして図示を省略した光偏向器の偏向反射
面を符号「１」で表し、倍率調整レンズ２３の偏向反射
面側の面（前面）及び被走査面側の面（後面）を符号
「２」及び「３」でそれぞれ表し、本発明にかかる凸レ
ンズ２２の偏向反射面側の面（前面）及び被走査面側の
面（後面）を符号「４」及び「５」でそれぞれ表してお
り、レンズ面の主副各方向における曲率半径ｒi ，ｒ’
i、ｉ番目の面から（ｉ＋１）番目の光軸上の間隔ｄi
、波長７８０ｎｍに対する屈折率ｎi は、以下のよう
な値にて構成されている。The deflecting / reflecting surface of the optical deflector (not shown) is denoted by reference numeral "1", and the deflecting / reflecting surface side (front surface) and the scanned surface side (rear surface) of the magnification adjusting lens 23 are denoted by reference numeral "1". 2 ”and“ 3 ”, respectively, and the surface on the deflecting reflection surface side (front surface) and the surface on the scanned surface side (rear surface) of the convex lens 22 according to the present invention are represented by reference numerals“ 4 ”and“ 5 ”, respectively. , The radii of curvature ri and r 'in the main and sub directions of the lens surface.
i, distance di on the (i + 1) th optical axis from the ith surface
The refractive index ni for a wavelength of 780 nm is constituted by the following values.
【００２２】 ｉ ｒi ｒ’i ｄi ｎi １ 0.0000 0.0000 16.9000 1.00000 ２ 0.0000 0.0000 2.0000 1.48601 ３ 0.0000 6.8000 13.5000 1.00000 ４ 127.4000 127.4000 16.9000 1.48601 ５ -75.1700 -12.3800 95.7000 1.00000 Ir r'i di ni 1 0.0000 0.0000 16.9000 1.00000 2 0.0000 0.0000 2.0000 1.48601 3 0.0000 6.8000 13.5000 1.00000 4 127.4000 127.4000 16.9000 1.48601 5 -75.1700 -12.3800 95.7000 1.00000
【００２３】第４面は、上記第１実施形態と同様な非球
面ｘからなり、非球面係数は、 ｋ＝ 0.00000E+00 ａ＝-0.10728E-05 ｂ＝ 0.35661E-09 ｃ＝ 0.00000E+00 ｄ＝-0.44641E-16 である。The fourth surface is made of the same aspherical surface x as in the first embodiment, and the aspherical surface coefficient is k = 0.0000E + 00 a = -0.10728E-05 b = 0.56661E-09 c = 0.0000E +00 d = -0.44641E-16.
【００２４】また焦点距離ＦＬは、 ＦＬ＝100.002 であり、 Ｐr ＝１３．１ θ ＝８０° Ｐx ＝１０．１２ Ｐy ＝ ８．８９ である。The focal length FL is FL = 100.002, and Pr = 13.1 θ = 80 ° Px = 10.12 Py = 8.89.
【００２５】尚、第５面は凸レンズ２２の被走査面側の
面（後面）であり、ｒ5＝-75.1700，ｒ’5＝-12.3800で
表されるように、主走査方向及び副走査方向の両方向に
正のパワーを有し、かつ中心光軸に平行で主走査方向に
直交する平面による断面が主走査方向に一定である面形
状を備えている。このような第２実施形態にかかる像面
湾曲特性及びｆθ特性を、図７（ａ）及び（ｂ）にそれ
ぞれ示す。このうち図７（ａ）中の破線は主走査方向の
像面を表し、図中実線は副走査方向の像面を表してい
る。The fifth surface is a surface (rear surface) of the convex lens 22 on the side of the surface to be scanned, and is represented by r5 = -75.1700 and r'5 = -12.3800 in the main scanning direction and the sub-scanning direction. It has a surface shape that has a positive power in both directions and has a constant cross section in a plane parallel to the central optical axis and perpendicular to the main scanning direction in the main scanning direction. FIGS. 7A and 7B show the field curvature characteristic and the fθ characteristic according to the second embodiment, respectively. Among these, the broken line in FIG. 7A indicates the image plane in the main scanning direction, and the solid line in the figure indicates the image plane in the sub-scanning direction.
【００２６】なおこの第２実施形態における倍率調整レ
ンズ２３は、ｒ2＝ｒ’2＝0.0000，ｒ3＝0.0000，ｒ’3
＝6.8000で表されるシリンドリカル凹レンズからなり、
副走査方向の焦点距離を短くすることによって副走査方
向の変動を小さく抑えようとするときに主走査方向と副
走査方向の像面を一致させる機能を有している。The magnification adjusting lens 23 according to the second embodiment has a function of r2 = r'2 = 0.000, r3 = 0.000, r'3.
Consists of a cylindrical concave lens represented by = 6.8000,
When the variation in the sub-scanning direction is to be reduced by shortening the focal length in the sub-scanning direction, a function of matching the image planes in the main scanning direction and the sub-scanning direction is provided.
【００２７】次に図８に示されている本発明の第３実施
形態における光走査光学系は、上述したアナモフィック
面を有する１枚の凸レンズ２４から構成されているが、
上記凸レンズ２４の偏向面側すなわち回転多面鏡側に、
副走査方向倍率を下げるための倍率調整レンズ２５が配
置されている。Next, the optical scanning optical system according to the third embodiment of the present invention shown in FIG. 8 includes one convex lens 24 having the above-described anamorphic surface.
On the deflection surface side of the convex lens 24, that is, on the rotating polygon mirror side,
A magnification adjusting lens 25 for lowering the magnification in the sub-scanning direction is arranged.
【００２８】そして図示を省略した光偏向器の偏向反射
面を符号「１」で表し、倍率調整レンズ２５の偏向反射
面側の面（前面）及び被走査面側の面（後面）を符号
「２」及び「３」でそれぞれ表し、本発明にかかる凸レ
ンズ２４の偏向反射面側の面（前面）及び被走査面側の
面（後面）を符号「４」及び「５」でそれぞれ表したと
き、レンズ面の主副各方向における曲率半径ｒi ，ｒ’
i、ｉ番目の面から（ｉ＋１）番目の光軸上の間隔ｄi
、波長７８０ｎｍに対する屈折率ｎi は、以下のよう
な値にて構成されている。The deflecting / reflecting surface of the optical deflector (not shown) is denoted by reference numeral "1", and the deflecting / reflecting surface side (front surface) and the scanned surface side (rear surface) of the magnification adjusting lens 25 are denoted by reference numeral "1". When the surface on the deflecting reflection surface side (front surface) and the surface on the scanned surface side (rear surface) of the convex lens 24 according to the present invention are represented by reference numerals “4” and “5”, respectively. , The radii of curvature ri and r 'in the main and sub directions of the lens surface.
i, distance di on the (i + 1) th optical axis from the ith surface
The refractive index ni for a wavelength of 780 nm is constituted by the following values.
【００２９】 ｉ ｒi ｒ’i ｄi ｎi １ 0.0000 0.0000 14.6000 1.00000 ２ -36.4600 -36.4600 2.2000 1.48601 ３ -36.4600 7.3000 10.9000 1.00000 ４ 256.0000 256.0000 16.0000 1.48601 ５ -61.8500 -11.0800 99.2000 1.00000 Irir'idinni 1 0.0000 0.0000 14.6000 1.00000 2 -36.4600 -36.4600 2.2000 1.48601 3 -36.4600 7.3000 10.9000 1.00000 4 256.0000 256.0000 16.0000 1.48601 5 -61.8500 -11.0800 99.2000 1.00000
【００３０】第１面は、光偏向器の偏向反射面であり、
第３面はｒ3＝-36.4600，ｒ’3＝7.3000であるアナモフ
ィック面である。また第２面及び第４面は、以下の式で
表される回転非球面ｘからなり、 ｘ＝（１／ｒ）ｙ2 ／｛１＋√［１−（１＋ｋ）ｙ2 ／
ｒ2 ］ ｝＋ａｙ4 ＋ｂｙ6 ＋ｃｙ8 ＋ｄｙ10＋ｅｙ12 但し、ｒ＝ｒ2 ＝ｒ’2 又は ｒ＝ｒ4 ＝ｒ’4 第２面における非球面係数は、 ｋ＝ 0.00000E+00 ａ＝ 0.00000E+00 ｂ＝ 0.12132E-08 ｃ＝ 0.00000E+00 ｄ＝ 0.00000E+00 ｅ＝-0.00000E+00 第４面における非球面係数は、 ｋ＝ 0.00000E+00 ａ＝-0.77407E-06 ｂ＝ 0.24264E-09 ｃ＝ 0.00000E+00 ｄ＝-0.22321E-16 ｅ＝ 0.00000E+00 である。The first surface is a deflecting / reflecting surface of the optical deflector,
The third surface is an anamorphic surface where r3 = -36.4600 and r'3 = 7.3000. The second surface and the fourth surface are each composed of a rotating aspheric surface x represented by the following equation: x = (1 / r) y 2 / {1 +} [1- (1 + k) y 2 /
r 2]} + ay 4 + by 6 + cy 8 + dy 10 + ey 12 where, r = r2 = r'2 or r = r4 = r'4 The aspherical coefficients of the second surface, k = 0.00000E + 00 a = 0.00000E +00 b = 0.12132E-08 c = 0.00000E + 00 d = 0.00000E + 00 e = -0.00000E + 00 The aspheric coefficient on the fourth surface is k = 0.00000E + 00 a = -0.777407E-06 b = 0.24264E-09 c = 0.00000E + 00 d = -0.22321E-16 e = 0.00000E + 00
【００３１】また焦点距離ＦＬは、 ＦＬ＝99.99 であり、 Ｐr ＝１６．０６ θ ＝８０° Ｐx ＝１２．４９ Ｐy ＝１１．４２ である。Further, the focal length FL is FL = 99.99, and Pr = 16.06 θ = 80 ° Px = 12.49 Py = 11.42.
【００３２】また、第５面は凸レンズ２４の被走査面側
の面（後面）であり、ｒ5＝-61.8500，ｒ’5＝-11.0800
で表される、主走査方向及び副走査方向の両方向に正の
パワーを有し、かつ中心光軸に平行で主走査方向に直交
する平面による断面が長手方向に一定である面形状とな
っている。このような第３実施形態にかかる像面湾曲特
性及びｆθ特性を、図９（ａ）及び（ｂ）にそれぞれ示
す。このうち図９（ａ）中の破線は、主走査方向の像面
を表し、図中実線は副走査方向の像面を表している。The fifth surface is the surface (rear surface) of the convex lens 24 on the surface to be scanned, and r5 = -61.8500, r'5 = -11.0800.
Has a positive power in both the main scanning direction and the sub-scanning direction, and has a surface shape in which a cross section by a plane parallel to the central optical axis and orthogonal to the main scanning direction is constant in the longitudinal direction. I have. FIGS. 9A and 9B show the field curvature characteristic and the fθ characteristic according to the third embodiment, respectively. Among these, the broken line in FIG. 9A represents the image plane in the main scanning direction, and the solid line in the figure represents the image plane in the sub-scanning direction.
【００３３】なおこの第３実施形態における倍率調整レ
ンズ２５は、符号３で示す面が副走査方向に負のパワー
（発散性）を持つトーリックレンズからなり、副走査方
向の焦点距離を短くすることによって副走査方向の変動
を小さく抑えるときに主走査方向と副走査方向の像面を
一致させる機能を有している。In the magnification adjusting lens 25 according to the third embodiment, the surface indicated by reference numeral 3 is a toric lens having negative power (divergence) in the sub-scanning direction, and the focal length in the sub-scanning direction is reduced. When the fluctuation in the sub-scanning direction is suppressed to a small value, the image plane in the main scanning direction and the image plane in the sub-scanning direction are matched.
【００３４】さらに図１０に示されている本発明の第４
実施形態における光走査光学系も、上述したアナモフィ
ック面を有する１枚の凸レンズ２６から構成されている
が、上記凸レンズ２６の偏向面側すなわち回転多面鏡側
に、副走査方向倍率を下げるための倍率調整レンズ２７
が配置されている。The fourth embodiment of the present invention shown in FIG.
The optical scanning optical system in the embodiment is also constituted by one convex lens 26 having the above-described anamorphic surface. However, a magnification for reducing the magnification in the sub-scanning direction is provided on the deflecting surface side of the convex lens 26, that is, on the rotating polygon mirror side. Adjustable lens 27
Is arranged.
【００３５】そして図示を省略した光偏向器の偏向反射
面を符号「１」で表し、倍率調整レンズ２５の偏向反射
面側の面（前面）及び被走査面側の面（後面）を符号
「２」及び「３」でそれぞれ表し、本発明にかかる凸レ
ンズ２６の偏向反射面側の面（前面）及び被走査面側の
面（後面）を符号「４」及び「５」でそれぞれ表したと
き、レンズ面の主副各方向における曲率半径ｒi ，ｒ’
i、ｉ番目の面から（ｉ＋１）番目の光軸上の間隔ｄi
、波長７８０ｎｍに対する屈折率ｎi は、以下のよう
な値にて構成されている。The deflecting / reflecting surface of the optical deflector (not shown) is denoted by reference numeral “1”, and the deflecting / reflecting surface side (front surface) and the scanned surface side (rear surface) of the magnification adjusting lens 25 are denoted by reference numeral “1”. When the surface on the deflecting reflection surface side (front surface) and the surface on the scanned surface side (rear surface) of the convex lens 26 according to the present invention are represented by reference numerals “4” and “5”, respectively. , The radii of curvature ri and r 'in the main and sub directions of the lens surface.
i, distance di on the (i + 1) th optical axis from the ith surface
The refractive index ni for a wavelength of 780 nm is constituted by the following values.
【００３６】 ｉ ｒi ｒ’i ｄi ｎi １ 0.0000 0.0000 19.0000 1.00000 ２ -50.6400 -50.6400 2.2000 1.48601 ３ -51.3200 15.8000 3.3000 1.00000 ４ 280.0000 280.0000 16.0200 1.48601 ５ -58.8000 -10.0000 99.5819 1.00000 Ir r'i di ni 1 0.0000 0.0000 19.0000 1.00000 2 -50.6400 -50.6400 2.2000 1.48601 3 -51.3200 15.8000 3.3000 1.00000 4 280.0000 280.0000 16.0200 1.48601 5 -58.8000 -10.0000 99.5819 1.00000
【００３７】このとき上記第２面における非球面及び第
３面におけるアナモフィック面の主走査平面内の形状ｘ
は、 ｘ＝（１／ｒ）ｙ2 ／｛１＋√［１−（１＋ｋ）ｙ2 ／
ｒ2 ］ ｝＋ａｙ4 ＋ｂｙ6 ＋ｃｙ8 ＋ｄｙ10＋ｅｙ12 で表され、第２面における非球面係数は、 ｋ＝ 0.00000E+00 ａ＝-0.16800E-05 ｂ＝ 0.60300E-09 ｃ＝-0.16600E-10 ｄ＝0.987000E-13 ｅ＝-0.12800E-17 第３面における非球面係数は、 ｋ＝ 0.00000E+00 ａ＝ 0.00000E+00 ｂ＝ 0.00000E+00 ｃ＝ 0.00000E+00 ｄ＝ 0.38000E-13 ｅ＝ 0.00000E+00 である。At this time, the shape x in the main scanning plane of the aspheric surface on the second surface and the anamorphic surface on the third surface
Is, x = (1 / r) y 2 / {1 + √ [1- (1 + k) y 2 /
r 2]} + ay expressed in 4 + by 6 + cy 8 + dy 10 + ey 12, aspherical coefficients of the second surface, k = 0.00000E + 00 a = -0.16800E-05 b = 0.60300E-09 c = -0.16600 E-10 d = 0.987000E-13 e = -0.12800E-17 The aspherical coefficient on the third surface is k = 0.00000E + 00 a = 0.00000E + 00 b = 0.00000E + 00 c = 0.00000E + 00 d = 0.38000E-13 e = 0.00000E + 00.
【００３８】また焦点距離ＦＬは、 ＦＬ＝100.07 であり、 Ｐr ＝１１．６ θ ＝８０° Ｐx ＝８．９７ Ｐy ＝７．９６ である。The focal length FL is FL = 100.07, and Pr = 11.6.theta. = 80.degree. Px = 8.97Py = 7.96.
【００３９】このような第４実施形態にかかる像面湾曲
特性及びｆθ特性を、図１１（ａ）及び（ｂ）にそれぞ
れ示す。このうち図１１（ａ）中の破線は主走査方向の
像面を表し、図中実線は副走査方向の像面を表してい
る。FIGS. 11A and 11B show the field curvature characteristic and the fθ characteristic according to the fourth embodiment, respectively. Of these, the broken line in FIG. 11A represents the image plane in the main scanning direction, and the solid line in the figure represents the image plane in the sub-scanning direction.
【００４０】なおこの第４実施形態における倍率調整レ
ンズ２７の符号３で示す面は、中心光軸に平行で主走査
方向に直交する平面による断面が長手方向に一定である
面形状を持ち副走査方向に負のパワーを持つアナモフィ
ックレンズからなり、副走査方向の焦点距離を短くする
ことによって副走査方向の変動を小さく抑えるときに主
走査方向と副走査方向の像面を一致させる機能を有して
いる。The surface denoted by reference numeral 3 of the magnification adjusting lens 27 in the fourth embodiment has a surface shape in which a cross section of a plane parallel to the central optical axis and orthogonal to the main scanning direction is constant in the longitudinal direction and has a sub scanning direction. It consists of an anamorphic lens with negative power in the direction, and has a function to match the image plane in the main scanning direction and the sub-scanning direction when reducing the fluctuation in the sub-scanning direction by shortening the focal length in the sub-scanning direction. ing.
【００４１】以上本発明者によってなされた発明を実施
形態に基づき具体的に説明したが、本発明は上記実施形
態に限定されるものではなく、その要旨を逸脱しない範
囲で種々変形可能であるというのはいうまでもない。例
えば、光偏向器としては、上記各実施形態のようなポリ
ゴンミラー等の回転多面鏡に限定されることはなく、回
転単面鏡や回転２面鏡等のように等角速度的に偏向させ
るものであれば同様に適用することが可能である。Although the invention made by the present inventor has been specifically described based on the embodiments, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the gist of the invention. Needless to say. For example, the optical deflector is not limited to a rotary polygon mirror such as a polygon mirror as in each of the above embodiments, but may be one that deflects at a constant angular velocity such as a rotary single mirror or a rotary two-face mirror. If so, the same can be applied.
【００４２】[0042]
【発明の効果】以上述べたように本発明にかかる光走査
光学系は、被走査面側面が主走査方向及び副走査方向の
両方向に正のパワー（発散性）を有し、かつ中心光軸に
平行で主走査方向に直交する平面による断面形状が主走
査方向に一定であるアナモフィック面を有する１枚の凸
レンズによって構成したものであるから、主走査方向の
像面及びｆθ特性と副走査方向の像面湾曲の補正とを、
１枚の凸レンズにより得ることができ、光走査光学系の
構成を簡素化し、生産性を向上させることができる。As described above, in the optical scanning optical system according to the present invention, the side surface to be scanned has a positive power (divergence) in both the main scanning direction and the sub-scanning direction, and the central optical axis. The cross-sectional shape of the plane parallel to the plane and perpendicular to the main scanning direction is the main running
Since it is constituted by a single convex lens having an anamorphic surface that is constant in the scanning direction, the correction of the image plane and fθ characteristics in the main scanning direction and the field curvature in the sub-scanning direction is performed.
It can be obtained by one convex lens, the configuration of the optical scanning optical system can be simplified, and the productivity can be improved.
【図１】本発明を適用した光走査光学系の原理的構成を
表した平面説明図である。FIG. 1 is an explanatory plan view showing a basic configuration of an optical scanning optical system to which the present invention is applied.
【図２】本発明の定義部位を表した原理的構成説明図で
ある。FIG. 2 is an explanatory diagram showing a principle configuration of a definition part of the present invention.
【図３】本発明の第１実施形態における光走査光学系を
表した平面説明図である。FIG. 3 is an explanatory plan view showing an optical scanning optical system according to the first embodiment of the present invention.
【図４】図３に表した第１実施形態による像面湾曲特性
（ａ）及びｆθ特性（ｂ）を表した線図である。FIG. 4 is a diagram illustrating a field curvature characteristic (a) and an fθ characteristic (b) according to the first embodiment illustrated in FIG. 3;
【図５】トーリック単レンズによる像面湾曲特性（ａ）
及びｆθ特性（ｂ）の一例を表した線図である。FIG. 5 is a field curvature characteristic of a toric single lens (a).
And FIG. 6 is a diagram showing an example of fθ characteristics (b).
【図６】本発明の第２実施形態における光走査光学系を
表した平面説明図である。FIG. 6 is an explanatory plan view showing an optical scanning optical system according to a second embodiment of the present invention.
【図７】図６に表した第２実施形態による像面湾曲特性
（ａ）及びｆθ特性（ｂ）を表した線図である。FIG. 7 is a diagram illustrating a field curvature characteristic (a) and an fθ characteristic (b) according to the second embodiment illustrated in FIG. 6;
【図８】本発明の第３実施形態における光走査光学系を
表した平面説明図である。FIG. 8 is an explanatory plan view showing an optical scanning optical system according to a third embodiment of the present invention.
【図９】図８に表した第３実施形態による像面湾曲特性
（ａ）及びｆθ特性（ｂ）を表した線図である。FIG. 9 is a diagram showing a field curvature characteristic (a) and an fθ characteristic (b) according to the third embodiment shown in FIG. 8;
【図１０】本発明の第４実施形態における光走査光学系
を表した平面説明図である。FIG. 10 is an explanatory plan view showing an optical scanning optical system according to a fourth embodiment of the present invention.
【図１１】図１０に表した第３実施形態による像面湾曲
特性（ａ）及びｆθ特性（ｂ）を表した線図である。FIG. 11 is a diagram showing a field curvature characteristic (a) and an fθ characteristic (b) according to the third embodiment shown in FIG. 10;
１ 回転偏向器 １ａ 偏向反射面 ２ アナモフィック凸レンズ ３ 感光体ドラム ３ａ 被走査面 DESCRIPTION OF SYMBOLS 1 Rotation deflector 1a Deflection / reflection surface 2 Anamorphic convex lens 3 Photoconductor drum 3a Scanned surface
Claims (5)
ともに、副走査方向において偏向反射面位置と被走査面
位置とを幾何光学的に略共役な関係とすることによっ
て、副走査方向の面倒れを補正する機能を備えた光走査
光学系において、 上記被走査面側の面が主走査方向及び副走査方向の両方
向に凸をなす１枚の凸レンズを有し、 上記凸レンズの被走査面側の面が、中心光軸に平行でか
つ主走査方向に直交する平面による断面形状に関して主
走査方向に一定の面形状を備えていることを特徴とする
光走査光学系。1. A surface tilt in the sub-scanning direction is provided by having an fθ function in the main scanning direction and making the position of the deflecting reflective surface and the position of the surface to be scanned substantially geometrically conjugate in the sub-scanning direction. An optical scanning optical system having a correction function, wherein the surface on the scanned surface side has one convex lens that is convex in both the main scanning direction and the sub-scanning direction, and the surface on the scanned surface side of the convex lens The optical scanning optical system is characterized in that the optical scanning optical system has a constant surface shape in the main scanning direction with respect to a cross-sectional shape of a plane parallel to the central optical axis and orthogonal to the main scanning direction.
のパワーを有する副走査方向の倍率調整用のレンズを配
置してなることを特徴とする光走査光学系。2. The optical scanning optical system according to claim 1, wherein a lens for adjusting magnification in the sub-scanning direction having negative power in the sub-scanning direction is arranged on the deflection surface side of the convex lens according to claim 1. An optical scanning optical system, comprising:
する光偏向器により等角速度的に偏向させ、上記光偏向
器により偏向された偏向光束を光走査光学系により被走
査面上に光スポットとして集光させて光走査を行なう光
走査光学系において、 上記光走査光学系は、上記被走査面側の面が主走査方向
及び副走査方向の両方向に凸をなす１枚の凸レンズを有
し、 上記凸レンズの被走査面側の面は、主走査方向及び副走
査方向の両方向に正のパワーを有し、かつ上記凸レンズ
の中心光軸に平行で主走査方向に直交する平面による断
面形状が上記主走査方向に一定の面形状を備えているこ
とを特徴とする光走査光学系。3. A light beam from a laser light source is deflected at an equal angular velocity by an optical deflector having a deflecting / reflecting surface, and the deflected light beam deflected by the optical deflector is spotted on a surface to be scanned by an optical scanning optical system. In the optical scanning optical system that performs light scanning by condensing light, the optical scanning optical system has one convex lens whose surface on the surface to be scanned is convex in both the main scanning direction and the sub-scanning direction. The surface on the scanned surface side of the convex lens has a positive power in both the main scanning direction and the sub-scanning direction, and has a cross-sectional shape formed by a plane parallel to the central optical axis of the convex lens and orthogonal to the main scanning direction. An optical scanning optical system having a constant surface shape in the main scanning direction.
レンズを配置してなることを特徴とする光走査光学系。4. The optical scanning optical system according to claim 3, wherein a lens for adjusting the magnification in the sub-scanning direction is arranged on the deflection surface side of the convex lens.
いて、 前記凸レンズの被走査面側の面は、走査光の中心光軸に
平行で主走査方向に直交する平面による断面形状が上記
主走査方向に関して同一の曲率半径であることを特徴と
する光走査光学系。5. The optical scanning optical system according to claim 1, wherein the surface of the convex lens on the surface to be scanned has a sectional shape defined by a plane parallel to a central optical axis of the scanning light and orthogonal to a main scanning direction. An optical scanning optical system having the same radius of curvature in the main scanning direction.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP34645795A JP3069281B2 (en) | 1994-12-26 | 1995-12-12 | Optical scanning optical system |
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP6-337327 | 1994-12-26 | ||
| JP33732794 | 1994-12-26 | ||
| JP34645795A JP3069281B2 (en) | 1994-12-26 | 1995-12-12 | Optical scanning optical system |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH08248341A JPH08248341A (en) | 1996-09-27 |
| JP3069281B2 true JP3069281B2 (en) | 2000-07-24 |
Family
ID=26575744
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP34645795A Expired - Fee Related JP3069281B2 (en) | 1994-12-26 | 1995-12-12 | Optical scanning optical system |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3069281B2 (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP4684470B2 (en) * | 2001-06-08 | 2011-05-18 | キヤノン株式会社 | Optical scanning device and image forming apparatus using the same |
-
1995
- 1995-12-12 JP JP34645795A patent/JP3069281B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPH08248341A (en) | 1996-09-27 |
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